n. 沉默寡言, 无言, 不太说话

[ noun ]
the trait of being uncommunicative; not volunteering anything more than necessary
<noun.attribute>

Taciturnity \Tac`i*tur"ni*ty\, n. [L. taciturnitas: cf. F.
taciturnit['e].]
Habitual silence, or reserve in speaking.

The cause of Addison's taciturnity was a natural
diffidence in the company of strangers. --V. Knox.

The taciturnity and the short answers which gave so
much offense. --Macaulay.